[SI-LIST] Re: XAUI - How to understand the "Compliance interconnect definition"
- From: Joseph.Schachner@xxxxxxxxxx
- To: edisonluckforever@xxxxxxxxx
- Date: Tue, 8 May 2012 11:02:20 -0400
The equation you gave is from section 47.4.1 Compliance interconnect
definition.
There is no section 47.41.
The way to understand this is to understand what the Compliance interconnect
is used for. It is used for "compliance testing" of a XAUI signal from a
PHY. It is meant to be about as bad as an interconnect is allowed to be. It
is used for making measurements on the transmitted signal. In the next
section, 47.4.2. it says far end Eye Diagram template tests are measured "at
the end of the compliance interconnect specified in 47.4.1." (It also
defines the load to be used at the far end for this test, separately).
The intent is to show that the transmitted signal can pass the far end
template after an interconnect at least this bad. Any system that you make
is expected to have BETTER (or equal, at worst) s21 than the compliance
interconnect. Your short channel, with much less s21, is great!
A compliant PHY's transmitted signal can pass the far end eye after going
through the "compliance interconnect". This means:
If a channel is worse than the compliance interconnect, then the testing
defined in 802.3 doesn't guarantee that the system with that channel will
work.
If a channel is better than the compliance interconnect - like your short
channel - then the testing defined in 802.3 is supposed to guarantee that
thesystem will work.
In short: the compliance interconnects' performance is not a goal, it is a
limit.
That is my understanding.
--- Joe S.
Edison Green ---05/08/2012 08:56:08 AM---I am confused when I study
XAUISPEC which in the Cause 47.41 of IEEE standard 802.3
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Edison Green <edisonluckforever@xxxxxxxxx> [IMG]
To:
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si-list@xxxxxxxxxxxxx [IMG]
Date:
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05/08/2012 08:56 AM [IMG]
Subject:
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[SI-LIST] XAUI - How to understand the "Compliance interconnect definition"
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I am confused when I study XAUI SPEC which in the Cause 47.41 of IEEE
standard 802.3
The Compliance interconnect definition describe as follow:
|S21|Ë?|S21|limit=-20log(e)*[a1*f^2+a2*f+a3*f^2]
This limit applies from DC to 3.125 GHz. The magnitude response above 3.125
GHz does not exceed -11.4 dB
ISI loss>4dB
The ISI loss,defined as the difference in magnitude response between two
frequencies, is greater than 4.0 dB between 312.5 MHz and 1.5625 GHz.
My question is that:
If my interconnect is shorter and the insertion losses(S21) is small also,
it maybe can't satisfy the "Compliance interconnect definition".
My interconnect charactar S21 will be
>|S21|limit=-20log(e)*[a1*f^2+a2*f+a3*f^2]
ISI loss will be <4db according to the definition(because abs(S21) may <4db)
In my mind, the shorter , the better, is it wrong?
How to understand the "Compliance interconnect definition"?
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